In recent years, in Korea, The amount of energy used for illumination reaches 18% of the total electric energy consumption amount, and is being greatly increased every year according to the highly-graded life environment. Nowadays, according to the worldwide tendency of conservation of earth environment, attempts for minimizing environmental pollution by efficiently using electric power through improvement of energy efficiency in the illumination field and through energy saving have been made very positively.
In general, for example, the most universally used electric devices are incandescent lamps, fluorescent lamps, and so on.
Since a typical illumination system using such electric device is provided with a power switch, which is turned on or off only by manual manipulation of a user, when the switch is in an on-status during absence of users, electric power is wasted due to continuous lighting of the electric device. Furthermore, the conventional illumination system has another problem in that the user has to manipulate the switch every time in order to turn on or off the electric device.
Such problems could be considerably solved by a human sensing illumination system disclosed recently.
The human sensing illumination system, which is installed in a frequently used area by people, such as the entrance, the front door, the hallway, stairs, the approach of an elevator, a warehouse, or others, automatically turns on an electric device when illuminance is lower than a predetermined value and when a user enters the area, and turns off the electric device when illuminance is higher than the predetermined value and when there is no user in the area. The human sensing illumination system provides illumination effect without operation of the switch by the user every time so as to improve convenience in use, and prevents waste of electric power so as to enable electric power to be efficiently used.
The human sensing illumination system will be described in more detail. The illumination system detects infrared rays (6.5□˜15□) generated from the human body, detects movement of the human body within a detection range at a long distance using a noncontact type pyroelectric sensor, transmits the infrared rays emitted from the human body to a pyroelectric type infrared sensor through a Fresnel lens, and transmits output voltage of the sensor to the first amplifier circuit. The first amplifier circuit serves as a band pass filter and an amplifier, and has the amplifying level of about 40 dB. The first amplified small signal is transmitted to the second amplifier circuit through a coupling condenser, and a signal outputted from the second amplifier circuit is transmitted to a window comparator. Square wave is outputted when signal of a pre-determined voltage and more is outputted, so that the electric device is turned on or off through a timer circuit and a triac on/off circuit.
Here, the triac on/off circuit includes an illumination sensor having a CDS element, which is made of compound where cadmium (Cd) and sulfur (S) are mixed with each other, whose resistance is rapidly reduced when light of a predetermined amount is detected, and whose resistance is increased to several hundreds of ohm (Ω). Therefore, the triac on/off circuit can provide the illumination environment corresponding to illuminance by selectively opening and closing the circuit according to a change of illuminance.
As described above, the human sensing illumination system having the above operation principle cannot show its function if any one of the above components is omitted, and it is impossible to use it in a sealed area, such as the toilet. That is, when the user enters the toilet, the human sensing illumination system detects the user and turns on the electric device. After that, when movement of the user is not detected, the human sensing illumination system turns off the electric device automatically after a predetermined time period, and thereby, it increases a feeling of uneasiness in easing nature.
Furthermore, the human sensing illumination system provides convenience to the user as providing the automatic turning-on and the automatic turning-off, but has a disadvantage in that the user cannot easily turn on or off the electric device manually according to the user's intention when the user wants to turn on the electric device for work under a state where the illuminance sensor detects above the predetermined value of illuminance. Moreover, the human sensing illumination system has several disadvantages in that the lifetime of the electric device is reduced due to frequent turning-on and turning-off when there is excessive change of illuminance due to a rapid weather change, in that the illuminance sensor is frequently in error, and in that the whole human sensing illumination system must be replaced when the illuminance sensor loses its function.
In addition, as described above, since the CDS element applied to the illuminance sensor is made of compound of cadmium (Cd) and sulfur (S), which is harmful to human body and is not environmentally friendly, the human sensing illumination system has another problem in that the compound must be gathered and treated separately.
As the CDS element applied to the illuminance sensor, there are a photoelectric tube, a phototransistor, a photodiode, and so on, which provide an effect similar to the CDS element. However, they cannot be applied to the human sensing illumination system as being too large and bulky, increase the manufacturing cost as being too expensive, and cannot realize a compact type human sensing illumination system. Furthermore, since they provide not the principle for opening or closing the corresponding circuit according to increase and decrease of a resistance value like the CDS element but the principle for generating electric current according to irradiation dose of light, the user must use the illumination system with care due to discharge of electricity, and so, they cannot be applied to the human sensing illumination system.
Therefore, required is an illumination apparatus, which can omit the illuminance sensor, which can turn on or off the electric device automatically and/or manually in order to improve convenience in use, which can prevent waste of electric power even though the electric device is turned on or off manually, to which various sensors besides the infrared sensor can be applied for detecting a moving body, and which provides a simple structure and an improved circuit design, thereby considerably reducing an error ratio and the manufacturing cost.